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Feedback on Backup-to-disk system (security)

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Hello all.

I was wondering if i could get your ideas and advice about a disk system im going to build for my company, mostly for usage as backup system.

its a basic 16 disk system, where i was planning the following configuration:

2x 8506-8 3ware Escalade controllers

16x 250gig disks, either WD or Maxtor

1 or 2 gigs of ram, and a good sized CPU.

My idea is to make an array on each of the controllers like this

Array 1 = Disk 1-7 in Raid5, Disk 8 as hotspare

Array 2 = Disk 9-15 in Raid5, Disk 16 as hotspare

Array 3 = Array 1 and Array 2 in Raid0. (windows 2003 software)

This should give me a theoretical writespeed of around 80MB/s or more, and still keep the security and maximizing the number of disks actually used for storage.

Only weak points i see in it, is a controller failure, or if the software stripeset explodes somehow.

Gentlemen, what are your thoughts?

Darking

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What none of you smart folks able to help me with this post, or are you all too busy writing answers to folks who ask, if Raid0 helps them in gaming :D

id rather know the experts opinion before i go out and invest 10.000$ on a server.

Darking

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Here is a thought. Why not buy an external IDE RAID solution like the Maxtronic Arena PA-8600 and save one more disk using one global spare, instead of two global spares?

The cost of the 16 drive box without drives is under $5,000. You can use two SCSI channels connected to a dual channel SCSI controller ($200) in the host computer and stripe on the controller (Adaptec HostRAID) or in Windows 2003 Server. Such solutions can sustain the 80MB/s solution that you are looking for.

It appears that you are looking for a stable solution and this might be a good solution instead of building your own from the chassis upward. There are other vendors other than Maxtronic - Medea, Nexsan, AXUS and Proware come to mind.

You are still stuck with the problem of controller failure. I am yet to witness one of those events.

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Sorry for not stating the function, a slight error.

Its basically storage for backup purpose.

Meaning that i will make my backup from our veritas backup server, to the storage server.

We need to backup roughly 300GB a day, and keep between 7 and 14 days, each weekend, a tape backup will be done from the storage server too. The backup window is 8 hours, and our current DLT simply cant do it in that emount of time.

The big plus of a disk system is also the restore time.

Unfortunately due to company policy the idea of incremental or differential isnt an option.

I like the NEXSAN products really, but im not looking for a SAN solution atm, since its going to get way to expensive compared to a simpler NAS solution like the one im wanting to make.

Darking

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well it sounds like a fine enough plan, then. i would consider having 2 hot spares per array just because you're striping them and they are ide disks. cpu speed shouldn't be that important, and 1gb of ram should be more than plenty. focus on your bus bandwidth and network speeds more than anything.

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The risk of the software RAID0 blowing up (and screwing your redundancy in the process) is a tad too high IMHO.

So looking at your requirements:

80MB/s Write

2.1-4.2TB Capacity (5-10 250GB drives)

If your capacity can be on the low end of that, RAID0+1 a single 8506-12

If your capacity has to be on the high end, run RAID0 arrays on 2x8506-8 and software RAID1 them.

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Well to be honest i doubt a 80MB/s writespeed is a requirement..

With 10MB/s i can still write the 300Gigs in five hours so im ok on that part.

I must admit i hadnt thought of using raid 0 and the software Raid1 then, that might be a idea..

Will it matter greatly that i use 5400 RPM disks, compared to 7200 RPM?

Since the price is alot different in those disks...

And will the Cache be of greater importance, 2 or 8MB pr drive?

Thanks for the good answers :)

Darking

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i've never seen microsoft windows software raid blow up, ever, in striping or mirroring. i would trust either of them as much as the other. get 7200rpm disks. 8mb isn't that much of a price premium, either.

if you run 0+1 on 2 8-port cards and have 6-7 250gb drives, you're only looking at 1.5-1.75tb of disk space total.

if it was my data i would buy a single 8506-12 and use 10 maxtor 8mb 250gb drives in raid5 with 2 hot spares. if you need more space, i still find your solution to be affable.

my primary concern would be disk failure (hot spares) and bus bandwidth.

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Well to be honest i doubt a 80MB/s writespeed is a requirement..

With 10MB/s i can still write the 300Gigs in five hours so im ok on that part.

I must admit i hadnt thought of using raid 0 and the software Raid1 then, that might be a idea..

Will it matter greatly that i use 5400 RPM disks, compared to 7200 RPM?

Since the price is alot different in those disks...

And will the Cache be of greater importance, 2 or 8MB pr drive?

Thanks for the good answers :)

Darking

The 8MB cache drives don't get you much in RAID arrays. As write speed isn't as big an issue, 5400RPM drives shouldn't hurt you that much either. I had reccomended the RAID10 over the RAID5 because of the write speed requirement. Going to RAID5 then RAID 1 would increase your degundancy over the RAID0 the RAID1 configuration. You can look at it like this:

Config (Hardware/Software)...(minimum #of drive failures before you're screwed)
0/0................................................0
5/0................................................1
0/1................................................1
5(w/1 hot spare)/0.................................2
5/1................................................2
5(w/1 hot spare)/1.................................3

Also keep in mind I wouldn't reccomend any config that uses software RAID0 over the top, as if that brakes, your done.

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degundancy :ph34r: ......try redundancy

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I haven't seen software RAID arrays break either, but I have seen the OS itself get hosed.

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Im not aware of the 3ware controllers supporting 50..

Plus another problem is that due to certain limitations, you cannot make arrays larger than 3 TB on the controllers..

Therefor i will end up with a problem at around 12 disks if i use 250GB disks.

Thats primarily the reason i made software strip, because the controllers cant make arrays over 3 TB

Darking

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Sorry for not stating the function, a slight error.

Its basically storage for backup purpose.

Meaning that i will make my backup from our veritas backup server, to the storage server.

We need to backup roughly 300GB a day, and keep between 7 and 14 days, each weekend, a tape backup will be done from the storage server too. The backup window is 8 hours, and our current DLT simply cant do it in that emount of time.

The big plus of a disk system is also the restore time.

Unfortunately due to company policy the idea of incremental or differential isnt an option.

I like the NEXSAN products really, but im not looking for a SAN solution atm, since its going to get way to expensive compared to a simpler NAS solution like the one im wanting to make.

Darking

For the purpose you state, why are you considering NAS? Can't you have a DAS solution? While NAS solutions will have a hard time exceeding 100MB/s of throughput, DAS (SCSI or Fiber Channel) can exceed that with ease.

Also, while your company policy is that incremental or differential backups are not an option, there may be solutions that store only one copy of a file so that you will not need 300GB times 7 or 14 days. So while you perform full backups every day, only incremental changes are stored. I use such a solution under UNIX that saves over 80% in storage requirement. I am not entirely sure if such software exists in the Windows world when the backup copies are stored under an NTFS filesystem copy and not in some proprietary backup archive/file format. It saves a lot of time while performing the backup, reducing the potential problems you run into with open files or hot databases. How do you plan to perform the backup to disk?

The reduced backup window also makes it possible to run more than one backup each day if required.

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The biggest problem with a fiberchannel or SCSI DAS solution is the money.

Ive tried looking around for stuff like that, compaq wich delivers our servers want over 50.000$ for one TB of storage. Its simply too high for our budget atm. plus i dont really need the big bandwith it gives me, 10-15MB/S should be sufficient.

We will use backup exec 8.6 for our backup needs, since thats what i have exeprience in, and it has always worked well, with disaster recovery options and stuff like that.

I know TSM is a solution that works like you describe, all tho i must admit that i myself am a bit nervous about those types of backups, i like to know that i have everything in one tape/disk etc. But grated its an option, altho TSM isnt cheap either, and i dont think i dare ask for a new backup program, since i just got Backup exec 8.6 last year ;)

Darking

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Could you detail the network topology, as it relates to your backup server, storage server, and all the servers that you are backing up?

When you say 300GB daily, is this the number for a full backup, or an incremental backup? Please detail the backup job(s).

Are you using any wiz-bang Veritas agents (SQL hot backup, exchange, etc...), or just bulk file backups? How many agents? Do all targets have an accelerator agent on them?

Why not place Veritas on the Storage server so as not so place an unnecessary load on the network between the two? Your post makes it sound as if you have a backup server that will be placing files on the storage server.

We will do our best to help you out.

Thank you for your time,

Frank Russo

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Im gonna answer the questions the best i can (lousy memory ;) )

Could you detail the network topology, as it relates to your backup server, storage server, and all the servers that you are backing up?

Well its a pretty simple setup really... i have 15 servers of different types, SQL, exchange, file servers. All of them attached to the network currently via 100Mbit network adapters, All of the servers will be replaced this winter, for newer models with Gbe. The servers themselves are attached to a Procurve 4108GL switch, with a backplane of about 36GBit.

When you say 300GB daily, is this the number for a full backup, or an incremental backup? Please detail the backup job(s).

Well basically its like this:

2 file server, around 600.000 documents, and different other types of files= 170GB

6 SQL servers, the biggest at 40GB database, all in all 65 GB database.

6 citrix servers, wich i just need to be able to Disaster recover= 30GB

1 exchange, with a priv.edb of around 10Gigs, and a pub.edb of around 1gig.

and 2 servers doing different oddjobs= 10 gigs

Are you using any wiz-bang Veritas agents (SQL hot backup, exchange, etc...), or just bulk file backups? How many agents? Do all targets have an accelerator agent on them?

We have IDR, accelerator, agents on all our servers and ofcause SQL and exchange on the respective servers

Alltho we generally atm. make backup of a flat dump file, and the logs, because of speed issues with making backup from the databases themselves. Our primary database server dumps to a internal DAS 3 times a day, but i only need to make one backup of it once a day.

Why not place Veritas on the Storage server so as not so place an unnecessary load on the network between the two? Your post makes it sound as if you have a backup server that will be placing files on the storage server.

That was sort of also my idea sooner or later, im going to test the speed my backupserver gives me(it runs some printing jobs too but thats it) at first, and then im gonna make a trial copy on the storage server, to see what that gives me. I can see the benefit of removing the backup task from our "production" servers.

But time will tell.

Darking

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